Process for the exploitation of petroleum deposits



Feb. 3, 1959 F. w. PLEUGER 2,

PROCESS FOR THE EXPLOITATION 0F PETROLEUM DEPOSITS Filed April 4, 1956BY I a I I I fiLA-Dz ATTORNEYS iinited States atent PROCESS FOR THEEXPLOITATION OF PETROLEUM DEPOSITS Friedrich Wilhelm Pleuger, Hamburg,Germany Application April 4, 1956, Serial No. 576,003

Claims priority, application Germany April 14, 1955 4 Claims. (Cl.166-45) The present invention relates to a process for the exploitationof petroleum and like deposits by transmitting thereto vibrations in thesonic and sub-sonic ranges.

More specifically, the invention relates to the transmission of suchvibrations by means of immersion pumps which are introduced into thedeposits by way of wells;

The invention is particularly adapted to the exploitation of oildeposits and the following disclosure is directed primarily to thisfield of usefulness.

The principal object of the invention is to increase the oil separationfactor and the economy of exploiting a deposit by diminishing theresistances which impede the passage of the petroleum through the layersof rock.

The accompanying drawing is a graph which schematically presents theeffect of the process of the present invention.

Before describing the invention, the following background should be keptin mind. As a general rule it has been possible heretofore to exploitpetroleum deposits or similar formations only up to approximately 40%.

Apparently the main cause of this low percentage and,

therefore, uneconomical exploitation, is that the petroleum droplets,due to electric charges, are combined with water particles and thisgreatly impedes the passage of the petroleum through the layers of rock.The water particles which accumulate on the petroleum droplets preventthe latter from coalescing, as occurs in the case of an emulsion, withthe result that a considerable increase in the resistance to drawing isdeveloped. In addition to the electrostatic forces just mentioned, otherphenomena which determine the oil separation factor of the oil carrier,are reduction of the surface stress and the viscosity of the oil. Thefactors just mentioned are responsible for the fact that the pressure ofthe oil deposit cannot exert its full effect because the phenomenadescribed represent a frictional resistance which causes the pressure todrop in the direction toward the well.

In carrying out my invention, I employ short-stroke pumps with anelectro-magnetic or electro-motive impulsi-on or driving means thereforadapted for the transmission of sonic and sub-sonic vibrations to thedeposit. The sound energy so transmitted causes the water-combineddroplets to vibrate so that, in an extremely short time, even if theamplitudes are small, they can free themselves from the adhering waterand coalesce with other similarly freed oil droplets. The oil threadswhich thus come into existence have much smaller resistance in the rockformation and can freely flow toward the well.

Another advantage resulting from the process of the present inventionarises by virtue of the reduction in the viscosity of the oil which isknown to be a consequence of the sound irradiation of substances of highmolecular weight.

My experiments have shown also that in order to obtain the improvementin yield which is characteristic of the invention, it is also importantto prevent the flowing movement of the oil which is set up by the soundirradiation referred to from being again interrupted because,

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otherwise, it could easily happen that the viscosity will again increaseand an emulsification be brought about. Therefore, in order to achieveuniform and uninterrupted fiow of oil from the well, it is preferable toemploy rapidly reciprocating pumps of essentially continuous drawingperformance because, in the conventional long-stroke and lever-systempumps, interruption of the flow during the discharge stroke is too long.

Rapidly oscillating movements of the drawing apparatus in a directionaxially .of the oil Well have the effect of transmitting the soundenergy to the oil column, and this acts as a coupling liquid to theoil-bearing rock where it causes the aggregation of the oil droplets.Where the drawing or pumping apparatus is equipped with a rapidlyreciprocating plunger the action, apparently, is as follows: the plungerface radiates the energy mainly in the direction of the longitudinalaxis of the well, and the sole or foot of the well (generally reinforcedwith concrete) has the effect of a reflector and makes possible theformation of standing or slowly progressing waves.

When struck by sound waves, the oil particles flow together and rise tothe surface and this aggregation of the particles takes placeessentially in the antinodes of oscillation. Even protected emulsionsand dispersions are destroyed in this manner. Therefore, it is safe toassume that sound waves are capable of piercing adsorbed films ofemulsifiers.

By cavitation, sound has the property of causing the formation of anemulsion at the surface contact of two non-mixable liquids. On the otherhand, it also brings about the destruction of said emulsion when theliquid is under great pressure corresponding in magnitude to a mercurycolumn of 2000 mm. This condition is encountered in a petroleum wellbecause of the high pressure of the deposit. The frequencies mostsuitable for sound irradiation of oil carriers according to the presentinvention lie within the boundaries of sub-sonic waves which have theproperty of expanding over wide areas without losing in intensity as theresult of damping. It is a well known physical phenomenon that soundvibrations of low frequency have a larger range than those of highfrequency. The frequencies of greatest importance for the presentprocess lie between 12 /2 and 60 C. P. S. (cycles per second). These areobtainable by electromagnetic, sub-sonic pumps.

In addition to said fundamental frequency (sub-sonic) it is alsoadvantageous to employ pumping apparatus for the present invention whichwill radiate frequencies within the range of 500 to 10,000 C. P. S.

By way of example, in order to demonstrate the efficacy of my newprocess, rapidly reciprocating piston diaphragm pumps were introducedinto certain oil wells and these pumps were arranged so that theiroscillating masses moved upward and downward in the direction of thelongitudinal axis of the well. The oscillating body and theelectro-magnetic or electro-motive means for driving it were combined ina cylindrical casing of almost the same diameter as that of the well andthis unit was suspended in the well riser. The sound was radiatedprimarily from the bottom face of the cylindrical body in a directiontoward the foot of the well and included components lying in theaforesaid supplemental range, whose frequencies were determined by thefundamental frequency, the number of slots in the driving motor, thenumber of teeth in a transmission gear, and the speed ratio between theimpeller and pump frequency.

As explained above, the reduction in pressure drop re sulting from thismethod of sound irradiation can be effectively utilized only whencontinuous movement of the oil is assured. Otherwise, the resistance toflow will again increase so that the sound irradiation becomesineffective. This continuity of oil flow is best secured if the rapidlyJ reciprocating short-stroke pump employed has the furthercharacteristic of being able to 'adapt itself automatically to thequantities of petroleum flowing in any given moment toward the well; inother words, the pump should operate in a manner which conforms directlyto the quantity of petroleum flowing, that is, the smaller the rate offlow, the smaller should be the volume drawn or pumped.

Based on tests, it has been determined that the stroke frequency of thepump, preferably, should be more than 750 strokes per minute, and also,that the length of the stroke should be less than 6 mm. Furthermore,this is also advisable because of the undesired degasification in thebore of the pump.

The process described above will often stimulate the yield of a well tosuch a degree that, even in cases where the well has ceased flowing, itwill again become productive. Such renewal of the flow of a well cannotbe ex plained or attributed merely to a sudden increase in the pressurein the oil deposit. Indeed, quite the contrary is the fact, namely thatas the result of clogging of the pores and other influences, theresistance to passage of the oil in the carrier has become greaterwhile, at the same time, the pressure in the deposit has diminished.This condition may become so great that an eruptive discharge ceasesearlier than if it were influenced merely by the pressure still existingin the deposit. With my invention, however, the resistances arediminished and this to such an extent that the available pressureremaining in the deposit becomes fully effective even to a degree wherea renewal of flow can again take place. Nevertheless such flow willagain recede or cease unless the oil, at the same time, is continuouslypumped from the well. If the stimulation incident to the process of theinvention leads to a renewal of the flow of the well it may be quitepossible to obtain a yield of oil without pump operation by means ofdiaphragms or throttling devices deposited in the well head aboveground. In any event, the final result is the attainment of an oilseparation factor of the oil carrier and the deposits respectively whichis much greater than that which is obtainable from conventional drawingor pumping procedures.

The accompanying drawing is a graphic presentation explaining the effectof the process of the present invention. Beside an ordinate on which thepressures are plotted, the drawing shows an oil well S, boredvertically, starting from the earth surface E in a deposit. The depositpressure is marked L; it would under normal conditions suffice to causean eruption of the well.

After the well has been exploited by the methods known in the past, theoil level' has dropped to the line 12 and the practically existingdischarge pressure in the well is marked A The greatest part of thedeposit pressure L has diminished on its way to the well, because of theresistance R to such an extent that no more oil can be drawn.

The application of the process according to the invention causes thedischarge resistance R to decrease to the resistance R which bringsabout the increase of the discharge pressure to A and the rising of theoil level to I1 By this method it is possible to fully utilize thedifference between the oil levels I1 and I1 Under certain circumstancesthe process according to the invention may reduce the resistance R, evento the resistance R in which case an eruption will take place, becausethe discharge pressure A, is greater than would correspond to a heightof drawing up to the earth surface E.

I claim:

1. The method for exploiting deep well petroleum dcposits whichcomprises simultaneously generating vibrations of two differentfrequencies within the bottom region of the well riser through which thepetroleum is pumped, and coupling the vibrations generated to the oilbearing strata surrounding said riser, one of said frequencies being inthe range of from 12 to 60 c. p. s. and the other being in the range offrom 500 to 10,000 c. p. s.

2. The method for exploiting deep well petroleum deposits whichcomprises utilizing submerged pumping means for simultaneouslygenerating vibrations of two different frequencies within the bottomregion of the well riser through which the petroletun is pumped, andcoupling the vibrations generated to the oil bearing strata surroundingsaid riser, one of said frequencies being in the range of from 12 to 60c. p. s. and the other being in the rangeof from 500 to 10,000 c. p. s.

3. A process according to claim 2 in which the submerged pumping meansincludes a pump having a stroke of not more than 6 mm., the strokefrequency being not less than 750/min.

4. A process according to claim 3 wherein the pump delivery increases inproportion to the pressure of flow.

References Cited in the file of this patent UNITED STATES PATENTS2,670,801 Sherbourne Mar. 2, 1954 2,680,485 Bodine June 8, 1954

1. THE METHOD FOR EXPLOITING DEEP WELL PETROLEUM DEPOSITS WHICHCOMPRISES SIMULTANEOUSLY GENERATING VIBRATIONS OF TWO DIFFERENTFREQUENCIES WITHIN THE BOTTOM REGION OF THE WELL RISER THROUGH WHICH THEPETROLEUM IS PUMPED, AND COUPLING THE VIBRATIONS GENERATED TO THE OILBEARING STRATA SURROUNDING SAID RISER, ONE OF SAID FREQUENCIES BEING INTHE RANGE OF FROM 12 TO 60 C. P. S. AND THE OTHER BEING IN THE RANGE OFFROM 500 TO 10.000 C. P. S.